Reinforcing bars, or rebars for short, are one of the most extensively used construction materials in modern buildings. To adapt the lengths of rebars to buildings of different specifications, and to solve the problem of insufficient length of a single rebar, it is common practice during the construction process to couple two rebars with a “mechanical rebar coupler”. The quality of such rebar couplers is of paramount importance because it has direct impact on the overall tensile strength and torsional strength of the coupled rebars.
Generally speaking, an “unprocessed rebar” is not an ideal or smooth cylinder but has ribs protruding from its surface. To prepare an end of an unprocessed rebar for coupling, it is required that the end be turned and threaded before it is locked into a rebar coupler. Conventionally, the rebar portion that is adjacent to the to-be-coupled end must be cold-rolled to form a smooth-surfaced cylindrical structure and thereby ensure the precision of subsequent turning and thread-rolling operations. However, as cold rolling, turning, and thread rolling are carried out by separate mechanisms, not only is it necessary for a construction company to buy machines of different functions, but also the entire processing process is time-consuming, simply considering the time it takes to transfer a cold-rolled rebar to a turning machine and a turned rebar to a thread-rolling machine. In addition, the machines take up considerable space in a factory.
Moreover, if the thread-rolling dies in the thread-rolling machine come into contact with the portion of a rebar that is not cold-rolled, it is very likely that the thread-rolling dies will be damaged by the protruding ribs. The issue to be addressed by the present invention, therefore, is to improve, integrate, and reduce the space occupied by, the foregoing mechanisms and to make adjustments in the processing procedure so as to increase the strength of a processed rebar and protect thread-rolling dies from damage.